The short answer is:
For the 2017 tax year, you can donate up to $2,177 as a married couple filing jointly, $1,089 as a single. You receive a dollar-for-dollar tax credit against your Arizona State Tax liability.
If you have no Arizona income tax liability, you cannot take the credit.
The longer answer is:
Although you only make one donation, Arizona state law requires us to break out your donation into two groups – Original tax credit and Overflow / Plus tax credit. Each of these can be used for different scholarship purposes and must be tracked separately on our end.
This may sound more complicated than it is. Simply put, by law you must first donate the maximum for the original tax credit, any additional you donate will go to the Overflow plus credit.
We will break out your donation the following way.
This primarily is something we need to track on our end, but we will break this all out for you on the receipt we send you for your taxes.